Lubricating oil supply system for rotary engine

ABSTRACT

A lubricating oil supply system for a rotary internal combustion engine and adapted to supply a lubricating oil onto the inner surface of the engine housing. The lubricating oil supply system has a diffuser disposed in the wall of a mixture supply pipe the diffuser serving to diffuse the lubricating oil into uniformly fine droplets which are mixed with air or the mixture of air and fuel supplied into the engine.

United States Patent ui Ishikawa LUBRICATING OIL SUPPLY SYSTEM FOR ROTARY ENGINE [75] Inventor: Yoshikazu Ishikawa, Tokyo, Japan [73] Assignee: Nissan Motor Company, Limited,

Yokohama City, Japan [22] Filed: Apr. 2, 1973 [21] Appl. No.: 346,763

[30] Foreign Application Priority Data Apr. 3, 1972 Japan 1. 47-33327 [52] US. Cl l23/8.09, 123/813, 123/196 R, 418/100, 123/73 AD [51] Int. Cl. F01C 21/04 [58] Field of Search 184/616; 123/196 R, 8.01, 123/809, 8.13; 418/83, 90, 100

[56] References Cited UNITED STATES PATENTS 2,313,387 3/1943 McArthur et al 418/100 Mar.4, 1975 3,140,700 7/1964 Nollinger 123/196 R X 3,738,453 6/1973 Boswell 184/616 3.764.234 10/1973 Morgan et a1. 123/801 FOREIGN PATENTS OR APPLICATIONS 1,451,730 3/1970 Germany 123/801 Primary Examiner-Manuel A. Antonakas 1 1 ABSTRACT A lubricating oil supply system for a rotary internal combustion engine and adapted to supply a lubricating oil onto the inner surface of the engine housing. The lubricating oil supply system has a diffuser disposed in the wall of a mixture supply pipe the diffuser serving to diffuse the lubricating oil into uniformly fine droplets which are mixed with air or the mixture of air and fuel supplied into the engine.

1 Claim, 1 Drawing Figure LUBRICATING OIL SUPPLY SYSTEM FOR ROTARY ENGINE This invention relates in general to rotary internal combustion engines and, more particularly, to a lubricating oil supply system for such engines.

As is well known, a rotary internal combustion engine is usually comprised of a housing having a cavity therein and a rotor disposed therein rotatable relative to the housing, about an axis laterally spaced from but parallel to the axis of the cavity. The rotor is journalled on the eccentric portion of a shaft which is co-axial with the housing and which in turn is journalled in bearings carried by the housing end walls. The housing has axially spaced end walls and a peripheral wall interconnecting the end walls to form the cavity, the inner surface of the cavity peripheral wall having a multi-lobed profile which preferably is basically an epitrochoid. The rotor has a peripheral surface with a plurality of circumferentially spaced apex portions, each carrying a radially movable seal for sealing engagement with the epitrochoidal inner surface of the housing peripheral wall to form a plurality of working chambers which vary in volume upon relative rotations of the housing and the rotor. In this construction, it has been a common practice to luricate the inner surfaces of the cavity for reducing friction between the surfaces of the housing and the rotor. There are two different kinds of methods proposed in the prior art for supplying the lubricating oil into the cavity of the engine housing. One of these methods is to have the lubricating oil mixed with liquid fuel, the mixture of which in turn is mixed with air to provide a combustible mixture which is supplied into the cavity of the engine housing. The lubricating oil contained in the combustible mixture thus supplied into the cavity of the engine housing is then applied onto the inner surfaces of the housing. A difficulty is encountered in this prior art in that, when the engine is operating under decelerating conditions, very little fuel is supplied into the engine and, therefore, lubricating oil is not supplied sufficiently into the engine resulting in excessive wear of the apex seals of the rotor.

Another expedient proposed in the prior art is to directly supply the lubricating oil into the cavity of the engine housing through, for example, a lubricating oil injection nozzle formed in slit-shape at the peripheral edge of the intake port of the housing. This practice is advantageous in that, even when the engine is operating under the decelerating condition, the lubricating oil is supplied into the cavity of the engine housing for satisfactory lubrication. However, a difficulty is still encountered in this prior practice in that it is difficult to inject the lubricating oil in such a manner as to apply the lubricating oil uniformly on the inner surfaces of the working chambers in the housing.

It is, therefore, an object of the present invention to provide a new and improved lubricating oil supply system for a rotary internal combustion engine of the trochoidal type.

Another object of the present invention is to provide a lubricating oil supply system which is capable of applying lubricating oil to an inner surface of a housing peripheral wall of a rotary internal combustion engine in a unform manner throughout various operating condition of the engine whereby improved engine perform ance efficiency is obtained.

Another object of the present invention is to provide a lubricating .oil supply system which is simple in construction and economical to manufacture.

Still another object of the present invention is to provide a lubricating oil suply system which can be readily installed in existing rotary internal combustion engines without causing substantial modifications or changes in the component parts of the engine.

According to the present invention, there is provided a lubricating oil supply system which is specifically suited for use in a rotary internal combustion engine of the trochoidal type. The rotary internal combustion engine to which the lubricating oil supply system of the present invention is applied commonly includes a housing having a cavity defined by an epitrochoidal inner surface of the housing peripheral wall and axilly spaced end walls, and a rotor rotatably disposed in the cavity of the housing. The housing has intake and exhaust ports formed in the peripheral wall of the engine housing, the intake port being connected to a mixture supply pipe which in turn is connected to an air inlet. The amount of air-fuel mixture supplied into the engine is controlled by a throttle valve operatively disposed in the intake port of the engine housing. In a preferred embodiment of the present invention, a lubricating oil supply nozzle is mounted on the mixture pipe upstream of the throttle valve and arranged to open to the mixture pipe through a diffusing means or a porous member. The diffusing means serves to diffuse the lubricating oil into fine droplets which are mixed with the mixture of fuel and air flowing through the mixture pipe during normal operating conditions of the engine. During decelerating conditions of the engine, the lubricating oil admitted through the diffusing means is mixed with air supplied from the air inlet and delivered to the cavity of the engine housing. Thus, the lubricating oil is uniformly distributed in the air or in the mixture of air and fuelso that, when the suction chamber in the cavity of the engine housing is compressed by the rotor, the lubricating oil is satisfactorily applied to the epitrochoidal inner surface of the housing peripheral wall.

These and other features and advantages of the present invention will become more apparent from the following description when taken in conjunction with a single FIGURE of the drawing, which illustrates a preferred embodiment of the lubricating oil supply system according to the present invention.

Referring to the single FIGURE of the drawing, there is shown a rotary internal combustion engine incorporating the lubricating oil supply system implementing the present invention. The rotary internal combustion engine is shown to include a housing 10 having a pcripheral wall formed with an epitrochoidal inner surface 12 defining a cavity 14 with axially spaced end walls (not shown) interconnected by the housng peripheral wall, and a rotor 16 rotatably disposed in the cavity 14 of the housing. The rotor 16 is journalled on an eccentric portion of a shaft 18, which is co-axial with the housing and which in turn is journalled in bearings carried by the housng end walls, although not shown. This rotor 16 has a peripheral surface with a plurality of circumferentially spaced apex portions, each carrying a radially movable seal 20 which sealingly engages the epitrochoidal inner surface 12 of the housing 10 to form a plurality of working chambers which vary in volume upon rotation of the rotor 16 relative to the housing 10. In the illustrated embodiment,

3 the working chambers 22 and 24 are shown as suction and exhaust chambers, respectively. The housing has peripheral intake and exhaust ports 26 and 28, which open to the suction chamber 22 and exhaust chamber 24, respectively. The exhaust port 28 is connected to an exhaust pipe 30 vented to theatmosphere to discharge exhaust gases from the exhaust chamber 24 to the atmosphere. The intake port 26 communicates with a mixture pipe 32, which in turn communicates with an air inlet 34 through which air is introduced into the mixture pipe 32. A fuel injection nozzle 36 is shown'as being mounted on the mixture pipe 32 for injecting liquid fuel thereinto which is mixed with air supplied from the air inlet 34 to provide an air-fuel mixture. lt should be noted that while, in the illustrated embodiment, the rotary engine is shown as at the type having a fuel injection nozzle, the rotary engine may be of the carburetor type. The air-fuel mixture thus provided is then supplied through the intake port 26 into the suction chamber 22 formed in the cavity 14. A throttle valve 38 is operatively disposed in the intake port 26 and rotatable therein to vary the flow of air-fuel mixture supplied to the suction chamber 22.

According to an important feature of the present invention, the lubricating oil is intended to be mixed with air or the mixture of air and fuel to be introduced into the suction chamber of the engine. To achieve this feature, the lubricating oil supply system, which is generally designated by the reference numeral 40, comprises a diffuser or porous member 42, which is shown as being received or mounted on the wall of the mixture supply pipe 32 in the path of fuel spray from the fuel injection nozzle 36 for diffusing the lubricating oil into uniformly fine droplets. The lubricating oil is supplied into the pipe 32 through the diffuser 42 by means of a lubricating oil supply unit 44 which is mounted on the outer wall of the mixture supply pipe 32 by some suitable fastener means such as bolts and nuts. As shown, the lubricating oil supply unit 44 has formed therein a lubricating oil distributing chamber 44a into which a lubricating oil supply pipe 46 opens. The lubricating oil distributing chamber 44a serves to evenly distribute the lubricating oil entering the diffuser 42 so that the lubricating oil can be diffused into air or the mixture of air and fuel in a satisfactory manner. The lubricating oil supply pipe 46 is connected through a metering pump 48 to a source of lubricating oil 50. It is to be understood that the metering pump 48 may be driven in relation with the engine speed whereby the metering pump 48 is synchronized with the engine speed to deliver the lubricating oil into the engine in desired amounts.

With the construction mentioned hereinabove, during normal operating condition of the engine, the lubricating oil is supplied through the pipe 46 into the lubricating oil distributing chamber 44a of the lubricating supply unit 44 by the action of the metering pump 48. The lubricating oil in the chamber 44a is then forced through and diffused by the diffuser 42 into fine droplets. Since, in this condition, the mixture of fuel and air is passed toward the diffuser 42 as shown by the dotted 'oil is applied uniformly on the epitrochoidal inner surface of the housing peripheral wall.

During decelerating condition of the engine, the fuel supply is shut off while only air is supplied into the suction chamber of the engine so that the lubricating oil in the form of fine droplets is mixed with air and carried thereby.

It will now be appreciated from the foregoing description that the lubricating oil supply system carrying out the present invention is capable of uniformly distributing the lubricating oil to the inner surface of the peripheral wall of the engine housing.

It will also be noted that the lubricating oil supply system of the present invention is capable of supplying the lubricating oil into the engine even when the engine is operating under decelerating condition.

It will further be understood that the lubricating oil supply system according to the present invention is supplied into the engine in desired-amounts at all times throughout various operating conditions of the engine since the system of the present invention is not affected by the suction created in the suction chamber of the engine especially when the engine is maintained in a decelerating condition.

What is claimed is:

1. In combination with a rotary internal combustion engine of the fuel injection type having an intake port, a mixture supply pipe connected to an air inlet and communicating with said intake port, a fuel injection nozzle mounted in said mixture supply pipe downstream of said air inlet and adapted for injecting fuel toward a limited part of a wall of said mixture supply pipe downstream of said fuel injection nozzle, a lubricating oil supply system comprising a source of lubricating oil, a metering pump communicating with said source of lubricating oil, a lubricating oil supply pipe communicating with said source of lubricating oil through said metering pump, a lubricating oil supply unit mounted on an outer wall of said mixture supply pipe and having a lubricating oil distributing chamber communicating with said lubricating oil supply pipe and opening into said mixture supply pipe at the limited part thereof, and a diffuser mounted in the wall of said mixture supply pipe at the limited part thereof in the path of fuel spray from said fuel injection nozzle, said lubricating oil distributing chamber of said unit distributing lubricating oil into said mixture supply pipe through said diffuser, whereby the lubricating oil is uniformly diffused into fine droplets which are mixed with the mixture of air and fuel to be supplied to the engine. 

1. In combination with a rotary internal combustion engine of the fuel injection type having an intake port, a mixture supply pipe connected to an air inlet and communicating with said intake port, a fuel injection nozzle mounted in said mixture supply pipe downstream of said air inlet and adapted for injecting fuel toward a limited part of a wall of said mixture supply pipe downstream of said fuel injection nozzle, a lubricating oil supply system comprising a source of lubricating oil, a metering pump communicating with said source of lubricating oil, a lubricating oil supply pipe communicating with said source of lubricating oil through said metering pump, a lubricating oil supply unit mounted on an outer wall of said mixture supply pipe and having a lubricating oil distributing chamber communicating with said lubricating oil supply pipe and opening into said mixture supply pipe at the limited part thereof, and a diffuser mounted in the wall of said mixture supply pipe at the limited part thereof in the path of fuel spray from said fuel injection nozzle, said lubricating oil distributing chamber of said unit distributing lubricating oil into said mixture supply pipe through said diffuser, whereby the lubricating oil is uniformly diffused into fine droplets which are mixed with the mixture of air and fuel to be supplied to the engine. 